Otarocyon
Encyclopedia
Otarocyon is an extinct genus "bone crushing dog" of the family Borophaginae
and a terrestrial
canine
which was small in size endemic to North America
during (Orellan
& Geringian
stage) of the Oligocene
epoch, ~33.9—20.6 Ma. Otarocyon existed for approximately .
, a specialized middle ear
, simple, tall premolar
teeth, and molars
that are incipiently adapted to a hypocarnivore
diet. Despite its Oligocene age, the skull of Otarocyon shows several striking similarities to the living Fennec Fox (Vulpes zerda), particularly in the structure of its middle ear. The similarities are probably convergent
, but they suggest that Otarocyon may have been similar in its appearance and habits.
In addition to its earlier age, O. macdonaldi differs from O. cooki in being smaller and in showing lesser development of the specializations that characterize the genus. O. macdonaldi is also the earliest known member of the subfamily Borophaginae, although the later appearing Archaeocyon
was more primitive.
Borophaginae
The subfamily Borophaginae is an extinct group of canids called "bone crushing dogs" that were endemic to North America during the Oligocene to Pliocene and lived roughly 36—2.5 million years ago and existing for approximately .-Origin:...
and a terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
canine
Canidae
Canidae is the biological family of carnivorous and omnivorous mammals that includes wolves, foxes, jackals, coyotes, and domestic dogs. A member of this family is called a canid . The Canidae family is divided into two tribes: Canini and Vulpini...
which was small in size endemic to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
during (Orellan
Orellan
The Orellan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 33,900,000 to 33,300,000 years BP, a period of . It is usually considered to fall within the Early Oligocene...
& Geringian
Geringian
The Geringian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 30,800,000 to 26,300,000 years BP, a period of . It is usually considered to fall within the Oligocene epoch...
stage) of the Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
epoch, ~33.9—20.6 Ma. Otarocyon existed for approximately .
Taxonomy
Otarocyon was a small borophagine characterized by a short, broad skullSkull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, a specialized middle ear
Middle ear
The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear has...
, simple, tall premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
teeth, and molars
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
that are incipiently adapted to a hypocarnivore
Hypocarnivore
A hypocarnivore is an animal that consumes less than 30% meat for its diet, the majority of which consists of nonvertebrate foods that may include fungi, fruits, and other plant material...
diet. Despite its Oligocene age, the skull of Otarocyon shows several striking similarities to the living Fennec Fox (Vulpes zerda), particularly in the structure of its middle ear. The similarities are probably convergent
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
, but they suggest that Otarocyon may have been similar in its appearance and habits.
Morphology
Fossil specimens of two individuals' body mass were examined by Legendre and Roth.- Specimen 1: 0.689 kg (1.5 lb)
- Specimen 2: 0.747 kg (1.6 lb)
Species
- O. macdonaldi from the early Oligocene ' onMouseout='HidePop("79954")' href="/topics/Orellan">OrellanOrellanThe Orellan North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 33,900,000 to 33,300,000 years BP, a period of . It is usually considered to fall within the Early Oligocene...
stage. Two specimens weighed 0.703 kg (1.5 lb) and 0.761 kg (1.7 lb). - O. cooki from the late Oligocene ' onMouseout='HidePop("4013")' href="/topics/Arikareean">ArikareeanArikareeanThe Arikareean North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology , typically set from 30,600,000 to 20,800,000 years BP, a period of . It is usually considered to overlap the Oligocene and Miocene epochs...
stage. Two specimens weighed 0.558 kg (1.2 lb) and 0.761 kg (1.7 lb).
In addition to its earlier age, O. macdonaldi differs from O. cooki in being smaller and in showing lesser development of the specializations that characterize the genus. O. macdonaldi is also the earliest known member of the subfamily Borophaginae, although the later appearing Archaeocyon
Archaeocyon
Archaeocyon is a small extinct genus of the Borophaginae within the family Canidae which inhabited most of North America during the Whitneyan stage through Geringian stage of the Oligocene epoch 33.3—26.3 Ma Archaeocyon existed for approximately .Species of Archaeocyon are among the earliest...
was more primitive.
Fossil distribution
- Cooper Gulch Locality No .1, Toston Formation, Lewis and Clark County, MontanaLewis and Clark County, Montana-National protected areas:* Flathead National Forest * Helena National Forest * Lewis and Clark National Forest * Lolo National Forest * Rocky Mountain Front Conservation Area -Demographics:...
~33.9—33.3 Ma. - Big Muddy Creek Site, Goshen County, Wyoming ~30.8—20.6 Ma.
- Godsell Ranch Site (SDSM V-5410), Sharps Formation, Shannon County, South DakotaShannon County, South DakotaAs of the census of 2000, there were 12,466 people, 2,785 households, and 2,353 families residing in the county. The population density was 6 people per square mile . There were 3,123 housing units at an average density of 2 per square mile...
~30.8—26.3 Ma. - Sharps Site (SDSM V-5359), Sharps Formation, Shannon County, South Dakota. ~30.8—26.3 Ma.
- Little Muddy Creek Site, Niobrara County, Wyoming, ~30.8—20.6 Ma.